The present invention relates to an ink-jet type recording head for generating pressure in pressure generating chambers substantially instantaneously by expansion/-contraction of piezoelectric vibrators or by heat elements to thereby jet ink droplets from nozzle openings in response to the change in pressure.
In an ink-jet type recording head in which dots on a recording medium are formed from ink droplets, printing with very high resolution can be made by reducing the ink droplet size, but it is necessary to increase the number of nozzle openings for the purpose of performing printing efficiently. Particularly in the case of an ink-jet recording head using piezoelectric vibrators as ink droplet jetting sources, it is necessary to increase the size of pressure generating chambers as to use the energy of the piezoelectric vibrators efficiently. However, this is contrary to the requirement of reducing the size of the recording head.
To resolve the aforementioned problems, there is generally used a method of setting walls which partition adjacent pressure chambers in such a manner as to be as thin as possible and of making the shape of the pressure generating chambers larger in the direction of the length thereof to thereby increase the volume thereof.
Such pressure generating chambers or reservoirs are formed by making through-holes in a spacer, i.e., a member for keeping the distance between a plate member and a nozzle plate at a predetermined value. So as to form through-holes coincident with pressure generating chambers having the required very small and complex shape, an etching technique is used generally.
A laminate of photosensitive resin films is used generally as a material constituting the aforementioned spacer. When such a photosensitive resin film laminate is used, there arises an advantage in that a desired pattern can be formed extremely accurately due to the fact that such materials are well suitable for photolithography, and due to the fact that the adhesive property thereof can be used so that no adhesive agent is required for fixing the laminate to the plate member and the nozzle plate. On the other hand, there is a disadvantage in that crosstalk, distortion, etc., can occur because of the low mechanical strength of the material, so that the quality in printing is lowered when this material is applied to a recording head with high resolution.
Moreover, since a plurality of resin films are laminated there is a risk of separation, so that the thickness of the spacer is limited by the characteristics of the material. There also arises a problem in that it is difficult to make the volume of each of the pressure generating chambers suitable for an ink-jet type recording head.
To solve the aforementioned problems, a proposal has been made in which a silicon single crystal substrate of crystal orientation (110) is used, and pressure generating chambers in the form of through-holes and ink supply ports and nozzle openings in the form of grooves of a depth providing a fluid resistance required for these openings are formed by anisotropic etching of a silicon single crystal substrate (see U.S. Pat. No. 4,312,008).
There, however, arises a problem in that not only is controlling of the manufacturing process complicated because it is necessary to precisely control the etching depth, but it is difficult to control the volume in positions necessary for securing fluid resistance to a precise degree, for instance in the ink supply ports, because the etched sectional shape is inherently a V-shape or a trapezoidal shape.